Re: [FFmpeg-devel] [PATCH v1] avcodec/jpeg2000htdec: check if block decoding will exceed internal precision

[Pierre-Anthony Lemieux <pal@sandflow.com>]

On Sat, Aug 12, 2023 at 11:39 AM Michael Niedermayer
<michael@niedermayer.cc> wrote:
>
> On Thu, Aug 10, 2023 at 04:48:56PM -0700, pal@sandflow.com wrote:
> > From: Pierre-Anthony Lemieux <pal@palemieux.com>
> >
> > Intended to replace https://patchwork.ffmpeg.org/project/ffmpeg/patch/20230802000135.26482-3-michael@niedermayer.cc/
> > with a more accurate block decoding magnitude bound.
> >
> > ---
> >  libavcodec/jpeg2000htdec.c | 32 +++++++++++++++++++++++++++++++-
> >  1 file changed, 31 insertions(+), 1 deletion(-)
> >
> > diff --git a/libavcodec/jpeg2000htdec.c b/libavcodec/jpeg2000htdec.c
> > index 2c4cea5dd9..713dba17e3 100644
> > --- a/libavcodec/jpeg2000htdec.c
> > +++ b/libavcodec/jpeg2000htdec.c
> > @@ -572,6 +572,14 @@ static int jpeg2000_decode_ht_cleanup_segment(const Jpeg2000DecoderContext *s,
> >
> >      const uint8_t *vlc_buf = Dcup + Pcup;
> >
> > +    /*
> > +     * Bound on the recision needed to process the codeblock. The number of
> > +     * decoded bit planes is equal to at most cblk->zbp + 2 since S_blk = P if
> > +     * there are no placeholder passes or HT Sets and P = cblk->zbp. See Rec.
> > +     * ITU-T T.814, 7.6.
> > +     */
> > +    int maxbp = cblk->zbp + 2;
> > +
> >      /* convert to raster-scan */
> >      const uint16_t is_border_x = width % 2;
> >      const uint16_t is_border_y = height % 2;
> > @@ -590,6 +598,10 @@ static int jpeg2000_decode_ht_cleanup_segment(const Jpeg2000DecoderContext *s,
> >          goto free;
> >      }
> >
> > +    /* do we have enough precision, assuming a 32-bit decoding path */
> > +    if (maxbp >= 32)
> > +        return AVERROR_INVALIDDATA;
>
> doesnt this need a goto free ?

Yes. Just pushed v2 of the patchset.

>
> thx
>
> [...]
>
> --
> Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
>
> No human being will ever know the Truth, for even if they happen to say it
> by chance, they would not even known they had done so. -- Xenophanes
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